What are the vibrating circles for?

Level 1:

Walk around the track, and see if you can find anything of interest.

Level 2:

There are five force fields along the winding track. Find the
dial near each one.

Level 3:

Next to the force field at each station, there is a dial with
5 possible positions. In each position, the force field vibrates in a different way. Take
note of the different shapes on the dial. Then, try standing inside the force field. You'll
notice that even if you don't move your mouse, you still jiggle a little bit. A ball rolling
down this track would definitely not be able to pass through unharmed...